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<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>03JS数据类型</title>
</head>
<body>
<script>
  //JS数据类型 = 原始类型 + 引用类型
  //原始类型:number string boolean null undefined
  var a = 1;
  var b = 9.9;
  console.log(a,typeof a,b,typeof b);
  var c = '你';
  var d = '你好';
  console.log(c,typeof c,d,typeof d);
  var f = true;
  var h = false;
  console.log(f,typeof f,h,typeof h);
  //声明了变量但未赋值，会得到undefined,未定义型
  var g ;
  console.log(g,typeof g)

  //引用类型 Object Number String Boolean Array....
  //1)自定义JS对象
  let obj = {name:'张三',age:18};
  console.log(obj,typeof obj)//{name:'张三',age:18}'object'
  console.log(obj.name,obj.age);//张三  18
  obj.like = '打飞机';
  console.log(obj.like);
  console.log(obj.play);//访问对象不存在的属性会得到undefined

  //JS数组
  let arr = ['典韦','鲁班','露娜',1,6.6,false];
  console.log(arr,typeof arr);
  console.log(arr[0]);
  console.log(arr[5]);
  console.log(arr[99]);//访问数组不存在的下标,会得到undefined
</script>
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</html>